Hi, According to the records of G. Newnham Collingwood, Vice Admiral Lord Collingwood's son-in-law (he married Sarah), Mary was married to Anthony Denny, and died rather young in 1822. As he puts it : "(....... for Mrs Denny was unhappily lost to her infant family, by her death in 1822.)". Thus it would seem unlikely that an immediate descendant migrated to America. There is a large number of Collingwoods in America, but then, it was - and still is -is a very large 'family', so that's not surprising. A Mary Collingwood could well have married William Rutherford, but I do not think that she was Lord Cuthbert's daughter. It would be interesting to find out just how she might have been related to him. Regards and good luck.